The internet is set for a radical shake-up after the organisation that oversees website names gave the green light to plans for a new way of creating web addresses.

The decision means that as well as millions of existing website addresses which end in .com or .co.uk, surfers will also be able to choose from sites with suffixes such as .bank, .sport or .bet.

A marathon meeting of the board of the Internet Corporation for Assigned Names and Numbers (Icann), which administers the development of the internet, ended in unanimous approval for the introduction of a new set of "top level" website addresses, bringing nearly three years of debate and planning to an end.

The process, which will begin in 2009, was described by the organisation's chairman, Paul Twomey, as "the biggest change to the way people find each other on the internet since its inception".

At first it is likely that new suffixes will be limited to businesses and other major organisations such as city councils, with cities such as New York and Berlin keen to create a whole selection of .nyc and .berlin addresses.

Some are concerned that opening the system up could encourage cybersquatting – where people unfairly register brand names in order to make money – or encourage criminals, who could find it easier to pose as banks or other legitimate organisations.

"If the domain name system is completely relaxed, cybersquatting will turn into a far greater problem, with companies struggling to protect their websites and intellectual property," said Thomas Herbert of Hostway, one of the world's largest web hosting companies.

"For example, Amazon would have to register many more domain names including Amazon.amazon, amazon.shopping, amazon.electronics. The list is practically endless, and the net result would be a much more chaotic and disorganised web."

However, buying one of this new generation of website addresses will not be cheap – some could cost as much as £250,000 – and applications would need to be approved by Icann.